avoid a few more copies (#2215)

nimbus/db/aristo/aristo_blobify.nim

@@ -133,7 +133,7 @@ proc blobify*(vtx: VertexRef): Result[Blob, AristoError] =
   ## Variant of `blobify()`
   var data: Blob
   ? vtx.blobify data
-  ok(data)
+  ok(move(data))
 
 proc blobify*(vGen: openArray[VertexID]; data: var Blob) =
   ## This function serialises a list of vertex IDs.
@@ -251,8 +251,7 @@ proc blobify*(filter: FilterRef): Result[Blob, AristoError] =
   ## ...
   var data: Blob
   ? filter.blobify data
-  ok data
-
+  ok move(data)
 
 proc blobify*(vFqs: openArray[(QueueID,QueueID)]; data: var Blob) =
   ## This function serialises a list of filter queue IDs.
@@ -425,7 +424,7 @@ proc deblobify*(data: openArray[byte]; T: type seq[VertexID]): Result[T,AristoEr
   ## Variant of `deblobify()` for deserialising the vertex ID generator state
   var vGen: seq[VertexID]
   ? data.deblobify vGen
-  ok vGen
+  ok move(vGen)
 
 proc deblobify*(data: Blob; filter: var FilterRef): Result[void,AristoError] =
   ## De-serialise an Aristo DB filter object

nimbus/db/aristo/aristo_hashify.nim

@@ -111,7 +111,7 @@ proc pedigree(
     wff.rev.withValue(toVid, val):
       val[].incl fromVid
     do:
-      wff.rev[toVid] = @[fromVid].toHashSet
+      wff.rev[toVid] = [fromVid].toHashSet
 
     # Remove unnecessarey sup-trie roots (e.g. for a storage root)
     wff.root.excl fromVid

nimbus/db/aristo/aristo_init/rocks_db/rdb_get.nim

@@ -47,7 +47,7 @@ proc getImpl(rdb: RdbInst; key: RdbKey): Result[Blob,(AristoError,string)] =
   # Correct result if needed
   if not gotData:
     res = EmptyBlob
-  ok res
+  ok move(res)
 
 # ------------------------------------------------------------------------------
 # Public functions
@@ -64,9 +64,10 @@ proc getKey*(rdb: var RdbInst; xid: uint64): Result[Blob,(AristoError,string)] =
   # Try LRU cache first
   let
     key = xid.toRdbKey KeyPfx
+  var
     rc = rdb.rdKeyLru.lruFetch(key)
   if rc.isOK:
-    return ok(rc.value)
+    return ok(move(rc.value))
 
   # Otherwise fetch from backend database
   let res = ? rdb.getImpl(key)
@@ -78,9 +79,10 @@ proc getVtx*(rdb: var RdbInst; xid: uint64): Result[Blob,(AristoError,string)] =
   # Try LRU cache first
   let
     key = xid.toRdbKey VtxPfx
+  var
     rc = rdb.rdVtxLru.lruFetch(key)
   if rc.isOK:
-    return ok(rc.value)
+    return ok(move(rc.value))
 
   # Otherwise fetch from backend database
   let res = ? rdb.getImpl(key)

nimbus/db/aristo/aristo_layers.nim

@@ -29,13 +29,13 @@ func dup(sTab: Table[VertexID,VertexRef]): Table[VertexID,VertexRef] =
 # Public getters: lazy value lookup for read only versions
 # ------------------------------------------------------------------------------
 
-func dirty*(db: AristoDbRef): HashSet[VertexID] =
+func dirty*(db: AristoDbRef): lent HashSet[VertexID] =
   db.top.final.dirty
 
-func pPrf*(db: AristoDbRef): HashSet[VertexID] =
+func pPrf*(db: AristoDbRef): lent HashSet[VertexID] =
   db.top.final.pPrf
 
-func vGen*(db: AristoDbRef): seq[VertexID] =
+func vGen*(db: AristoDbRef): lent seq[VertexID] =
   db.top.final.vGen
 
 # ------------------------------------------------------------------------------

nimbus/db/kvt/kvt_init/memory_db.nim

@@ -77,9 +77,9 @@ proc getKvpFn(db: MemBackendRef): GetKvpFn =
     proc(key: openArray[byte]): Result[Blob,KvtError] =
       if key.len == 0:
         return err(KeyInvalid)
-      let data = db.mdb.tab.getOrVoid @key
+      var data = db.mdb.tab.getOrVoid @key
       if data.isValid:
-        return ok(data)
+        return ok(move(data))
       err(GetNotFound)
 
 # -------------

nimbus/db/kvt/kvt_init/rocks_db.nim

@@ -84,14 +84,14 @@ proc getKvpFn(db: RdbBackendRef): GetKvpFn =
     proc(key: openArray[byte]): Result[Blob,KvtError] =
 
       # Get data record
-      let data = db.rdb.get(key).valueOr:
+      var data = db.rdb.get(key).valueOr:
         when extraTraceMessages:
           debug logTxt "getKvpFn() failed", key, error=error[0], info=error[1]
         return err(error[0])
 
       # Return if non-empty
       if 0 < data.len:
-        return ok(data)
+        return ok(move(data))
 
       err(GetNotFound)
 

nimbus/db/kvt/kvt_init/rocks_db/rdb_get.nim

@@ -51,7 +51,7 @@ proc get*(
 
   if not gotData:
     res = EmptyBlob
-  ok res
+  ok move(res)
 
 # ------------------------------------------------------------------------------
 # End

nimbus/db/kvt/kvt_utils.nim

@@ -90,10 +90,10 @@ proc get*(
   if key.len == 0:
     return err(KeyInvalid)
 
-  let data = db.layersGet(key).valueOr:
+  var data = db.layersGet(key).valueOr:
     return db.getBe key
 
-  return ok(data)
+  return ok(move(data))
 
 
 proc hasKey*(

nimbus/db/ledger/distinct_ledgers.nim

@@ -198,10 +198,10 @@ proc init*(
   mpt.toPhk.T
 
 proc fetch*(sl: StorageLedger, slot: UInt256): Result[Blob,void] =
-  let rc = sl.distinctBase.fetch(slot.toBytesBE)
+  var rc = sl.distinctBase.fetch(slot.toBytesBE)
   if rc.isErr:
     return err()
-  ok rc.value
+  ok move(rc.value)
 
 proc merge*(sl: StorageLedger, slot: UInt256, value: openArray[byte]) =
   const info = "StorageLedger/merge(): "